CVE-2026-109721: Incorrect boundary conditions in the JavaScript Engine: JIT component

Published Oct 13, 2026
·
Updated

Incorrect boundary conditions in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 158, Firefox ESR 153.5, Thunderbird 158, and Thunderbird 153.5.

Other sources

Incorrect boundary conditions in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 158 and Firefox ESR 153.5.

— Red Hat

Affected Software

17 affected componentsFixes available
Mozilla Thunderbird<153.5
153.5
ubuntu/mozjs52*
ubuntu/mozjs38*
ubuntu/mozjs68*
ubuntu/mozjs52*
ubuntu/mozjs102*
ubuntu/mozjs78*
ubuntu/mozjs91*
ubuntu/thunderbird*
ubuntu/mozjs102*
ubuntu/mozjs115*
Mozilla Firefox<158
158
Mozilla Firefox ESR<153.5
153.5
Mozilla Thunderbird<158
158
debian/firefox
159.0-1
debian/firefox-esr<=140.12.0esr-1~deb12u1, <=140.15.0esr-1~deb13u1
153.6.0esr-1~deb12u2153.6.0esr-1~deb13u1153.5.1esr-1153.6.0esr-1
debian/thunderbird<=1:140.12.0esr-1~deb12u1, <=1:140.12.0esr-1~deb13u1
1:153.6.0esr-1~deb12u21:153.6.0esr-1~deb13u11:153.5.0esr-11:153.6.0esr-1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 153.5
  2. Upgrade

    Upgrade to a fixed release to a version that resolves this vulnerability.

    Fixed in 158
  3. Upgrade

    Upgrade debian/firefox to a version that resolves this vulnerability.

    Fixed in 159.0-1
  4. Upgrade

    Upgrade debian/firefox-esr to a version that resolves this vulnerability.

    Fixed in 153.6.0esr-1~deb12u2Fixed in 153.6.0esr-1~deb13u1Fixed in 153.5.1esr-1Fixed in 153.6.0esr-1
  5. Upgrade

    Upgrade debian/thunderbird to a version that resolves this vulnerability.

    Fixed in 1:153.6.0esr-1~deb12u2Fixed in 1:153.6.0esr-1~deb13u1Fixed in 1:153.5.0esr-1Fixed in 1:153.6.0esr-1
  6. Upgrade

    Upgrade Firefox and Thunderbird to a version that resolves this vulnerability.

    Fixed in 158
  7. Upgrade

    Upgrade Firefox ESR and Thunderbird ESR to a version that resolves this vulnerability.

    Fixed in 153.5

Event History

Oct 13, 2026
CVE Published
via Mozilla·12:00 AM
Data Sourced
via Mozilla·12:00 AM
DescriptionSeverityAffected Software
Data Sourced
via Ubuntu·12:00 AM
RemedyDescriptionSeverityAffected Software
CVE Published
via MITRE·12:29 PM
Data Sourced
via MITRE·12:29 PM
Description
Data Sourced
via Red Hat·01:11 PM
DescriptionSeverityAffected Software
Data Sourced
via OSV·01:17 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·01:17 PM
DescriptionSeverityWeakness

Parent advisories

This vulnerability appears in the following advisories.

Peer vulnerabilities

Found alongside the following vulnerabilities.

Frequently Asked Questions

1

Which Firefox releases contain the fix?

The issue was fixed in Firefox 158 and Firefox ESR 153.5.

2

What should organizations do to remediate it?

Update Mozilla Firefox to version 158 or Mozilla Firefox ESR to version 153.5, as applicable.

Company

Resources

Contact

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